Hacker help: How to get the Trones to be green?

Materials: 3 x Trones

Description: Hi, I do have those nice Trones Boxes at home and thought about using them on my balcony for growing plants in it.

But I do not know exactly how I should do it - and therefor I am asking you all :)

I do have 2 ideas -

1) making holes on the top of the Trones but that would force me to lose space to put other plants on it.

2) open the Trones fill them up with earth - let the plants grow and if the winter comes - cut them of - close the Trones and everything is clean and ready for winter.

So what ideas do you IKEA hackers have for my Trones when the summer comes and the winter is gone :)

Cheers

~ Herbert Feutl, Austria